The present invention relates generally to the H.323 standard for transmitting audio and video data streams, and more particularly to extending the H.323 standard to support mobility in a multimedia communication system with services over packet-based networks.
Originally, the International Telecommunications Union (ITU) developed H.323 as an adaptation of H.320, which addresses videoconferencing over ISDN and other circuit-switched networks and services. H.320 was ratified in 1990, and corporations expanded their networks to include Local Area Networks (LANs) and LAN gateways to the Wide Area Network (WAN). Then, H.323 was expanded beyond being an extension of H.320 so that H.323 now covers the corporate intranets and packet-switched networks in general. The ITU published a set of standards for multimedia communication over packet-based networks (PBNs) under the H.323 designation, which includes standards for data channels, monitoring channels, and control channels. It includes provision of real-time audio, video and/or data communications. The H.323 components defined by the standard include: terminals, gateways, gatekeepers and multipoint control units (MCUs). The terminals provide real-time communications, must support audio/voice communications and optionally support data and video. The most common H.323 terminals are the applications that run on a personal computer (PC). H.323 gateways provide services to H.323 clients and allow communication with non-H.323 entities, such as communication between H.323 terminals and telephone in a circuit-switched network. Gatekeepers provide call control services for H.323 endpoints, e.g., address translation and bandwidth management. Gatekeepers are optional in the H.323 standard, but, if they are present, the endpoints must use the services of the gatekeepers. The H.323 standard specifies certain mandatory services that gatekeepers, if utilized, must provide. The multipoint control units provide support for conferences of three or more endpoints by managing conference resources, manage negotiations between the endpoints to specify which audio or video codec(s) to use and may manage the media stream. The H.323 standard defines how audio and video conferencing systems communicate over packet-switched networks defines call control and management practices for point-to-point and broadcast/multicast/unicast multipoint conferences, addresses QoS issues with a centralized gatekeeper that LAN administrators use to manage media traffic, bandwidth and user participation, and describes functionality that allows calls to connect from the LAN to the Public Switched Telephone Network (PST) as well as to other H.32x standards-based terminals.
In version 2 of the H.323 standard, video and audio data streams are compressed and packetized in accordance with a real-time transport protocol (RTP/RTCP) standard from the Internet Engineering Task Force (IETF) and are used to support video conferencing and other communications over the Internet. Packets include data and header information which facilitates detection of packet loss, detection of packet status and synchronization of the packets. The video data streams may use H.261, H.262, or H.263 protocols. Audio data streams may use G.711, G.722, G.723.1 G.728 or G.729 protocols. Generally, the H.323 standard supports teleconferencing in networks that utilize TCP/IP, such as, for example, the Internet.
The H.323 system supports interoperability and assumes that users, terminals, and services are fixed. If an H.323 terminal is moved form one network to another, its point of attachment or network address changes. In this situation, the address of the mobile terminal needs to be resolved to set up a new call or continue a same call. Thus, there is a need for an H.323 mobility architecture that provides for terminal, user and service mobility.
The present invention provides an H.323-based mobility architecture for real-time mobile multimedia communications and conferencing over packet-based networks wherein a plurality of H.323 mobility gatekeepers provide notification of H.323 mobility services availability by periodically multicast, broadcasting, and/or unicast a Mobility Gatekeeper Advertisement with a multicast/unicast address as appropriate. If needed, the mobile Terminal/Node/Entity can also multicast, broadcast, and/or unicast a discovery message seeking a gatekeeper that provides the mobility services. The protocol includes the steps of: detecting, by a Mobile Terminal/Node/Entity, whether it has changed its location in a given zone or domain where zone and (administrative) domain have been defined in accordance to ITU-T Recommendations H.323 and H.225.0. The abstraction of zone is such that it is managed by a gatekeeper while a domain consists of one or more zones. A domain may be administered by an administration (e.g., an Internet Service Provider (ISP), a corporation, a carrier network, etc.). The communications between the domains are via border elements (BEs). However, the border elements can communicate with the gatekeeper.
The present invention provides an H.323-based mobility system with protocol for real-time mobile multimedia communications and conferencing over packet-based networks wherein a plurality of H.323 mobility gatekeepers provide notification of H.323 mobility services availability by periodically broadcasting, multicasting or unicasting a Mobility Gatekeeper Advertisement with a multicast address. In this embodiment, the invention includes at least one H.323 Mobile Terminal/Node/Entity, at least one Base Station, a Home Location Database, a first Visitor Location Database, the first Mobile Switching Center, a second Visitor Location Database, and a second Mobile Switching Center.
The at least one H.323 Mobile Terminal, Node or Entity is arranged to broadcast, multicast or unicast an H.323 call, that, upon detecting at least one H.323 mobility gatekeeper of the plurality of H.323 mobility gatekeepers that support H.323 mobility services in a Location Area, Cell, or Zone of the Mobile Terminal, Node or Entity, Databases with a Home Location Database in the first Location Area/Cell/Zone via a first Mobile Switching Center, moves from the first Location Area/Cell/Zone to a second Location Area/Cell/Zone, registers locally, and sets up a mobile H.323-based call.
In the case of cellular wireless networking environment, the at least one Base Station is arranged to receive and/or send location information and H.323 calls in the first/second Location Area, Cell, or Zone, and is used for receiving and/or sending the location information for the Mobile Terminal, Node or Entity from/to a first and/or second Mobile Switching Center, and for receiving/sending calls from/to the first/second Mobile Switching Center for forwarding to a callee Mobile/Nonmobile Terminal/Node/Entity. The Home Location Database is arranged to receive and store Mobile Terminal, Node or Entity location information and send the location information to a first Visitor Location Database via a first Mobile Switching Center in the case of cellular wireless networking enviornment, and upon the H.323 Mobile Terminal/Node/Entity moving from the first Location Area, Cell, or Zone to the second Location Area, Cell or Zone, is utilized for receiving update location information and sending the update location information to a second Visitor Location Database via a second Mobile Switching Center for the second Location Area, Cell or Zone.
The first Visitor Location Database is arranged to receive the location information via the first Mobile Switching Center, and is used for storing and updating the location information.
Again, in the case of the cellular wireless networking environment, the first Mobile Switching Center is arranged to receive and acknowledge location information and, where the callee Mobile/Nonmobile Terminal, Node or Entity is in the first Location Area, Cell or Zone, and is used for setting up a call from the Mobile Terminal/Node/Entity to the callee Mobile/Nonmobile Terminal, Node, or Entity via a callee Base Station in the first Location Area/Cell/Zone.
The second Visitor Location Database is arranged to receive the location information via the second Mobile Switching Center, and is used for storing and updating the location information.
The second Mobile Switching Center is arranged to receive and acknowledge location information and, where a callee Mobile/Nonmobile Terminal, Node or Entity is in the second Location Area, Cell or Zone, for setting up a call from the Mobile Terminal, Node or Entity to the callee Mobile/Nonmobile Terminal, Node or Entity via a callee Base Station in the second Location Area, Cell or Zone.
The Home Location Database typically registers the Mobile Terminal/Node/Entity by sending registration information for the Mobile Terminal/Node/Entity to a first Visitor Location Database via the first Mobile Switching Center. When the Mobile Terminal/Node/Entity enters the second Location Area/Cell/Zone, the Mobile Terminal/Node/Entity may perform local registration by broadcasting/multicasting/unicasting a location update message that is forwarded by the Base Station, to the second Mobile Switching Center, which launches a registration query to a second Visitor Location Database, wherein the second Visitor Location Database updates location information of the Mobile Terminal/Node/Entity and sends the location information to the Home Location Database, upon receiving the location information that is updated, the Home Location Database sends a registration acknowledgement to the second Visitor Location Database and a registration cancellation message to the first Visitor Location Database, and the First Location Database acknowledges receipt of the registration cancellation message.
A Visitor Location Database address is generally determined for the Mobile Terminal/Node/Entity based on a mobile identification number of the Mobile Terminal/Node/Entity and is sent to the Home Location Database where due to the moving, the Mobile Terminal/Node/Entity belongs to the second Visitor Location Database.
A mobile H.323-based call may be set up when the Mobile Terminal/Node/Entity in the first Location Area/Cell/Zone initiates a call to a callee Mobile/Nonmobile Terminal/Node/Entity in a second Location Area/Cell/Zone via a Base Station in the first Location Area/Cell/Zone, the Base Station forwards the call to the first Mobile Switching Center, the first Mobile Switching Center determines an address of the callee Mobile/Nonmobile Terminal/Node/Entity and sends a location request to a Home Location Database which determines a callee Visitor Location Database of the callee Mobile/Nonmobile Terminal/Node/Entity and sends a route request message to a callee Mobile Switching Center serving the callee Mobile/Nonmobile Terminal/Node/Entity;
the callee Mobile Switching Center allocates a temporary local directory number to the Mobile Terminal/Node/Entity and sends a reply to the Home Registration Database together with the temporary local directory number, the Home Registration Database sends the temporary local directory number to the first Mobile Switching Center, and
the first Mobile Switching Center requests a call setup to the callee Mobile Switching Center. It may be mentioned that the Mobile Switching Center can be packet switches such as IP routers or ATM switches.
In the case of wireless LAN/wire-line LAN/wire-line networking environment, the H.323 mobile entity will also communicating as described above, however, there may not be base stations and base station switching centers.
Where desired, at least one of the plurality of H.323 mobility gatekeepers may provide for authentication of the mobile entities/users. The H.323 mobility services may be selected to include at least: address translation, admissions control, bandwidth control, and zone management.